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Chemical pulping involves dissolving lignin in order to extract the cellulose from the wood fiber. The different processes of chemical pulping include the Kraft process, which uses caustic soda and sodium sulfide and is the most common; alternatively, the use of sulfurous acid is known as the sulfite process, the neutral sulfite semichemical is treated as a third process separate from sulfite ...
The black liquor is an aqueous suspension of lignin residues, hemicellulose, and the inorganic chemicals used in the process. The black liquor comprises 15% solids by weight of which two thirds are organic chemicals and the remainder are inorganic. [3] Normally the organics in black liquor are 40-45% soaps, [4] 35-45% lignin and 10-15% other ...
It enabled the recovery and reuse of the inorganic pulping chemicals such that a kraft mill is a nearly closed-cycle process with respect to inorganic chemicals, apart from those used in the bleaching process. For this reason, in the 1940s, the kraft process superseded the sulfite process as the dominant method for producing wood pulp. [6]
Recycled paper products can also contain BPA, [66] although this can depend strongly on how it is recycled. Deinking can remove 95% of BPA, [9] with the pulp produced used to make newsprint, toilet paper and facial tissues. If deinking is not performed then the BPA remains in the fibers, paper recycled this way is usually made into corrugated ...
Found in plastics and paper, some of the potential mammary carcinogens include polysterene and polyamide, which are used in styrofoam to-go containers from restaurants and black plastic spatulas.
Many paper and bamboo straws contain PFAS, also called "forever chemicals," which might make them a less-than-ideal alternative to plastic, research suggests.
A black and white photographic print in a tray while being processed after exposure to light under a photographic enlarger. Typically three trays are used containing either developer, stop bath, or fixer, in that order. The print must then be rinsed in water to removed the fixer.
A new study from Belgian researchers found that paper straws had higher concentrations of long-lasting, water resistant "forever chemicals" than plastic or steel straws.